Generally, the water pressure transfer method is a method for floating on a water surface in a transfer tub a transfer film formed by a predetermined print pattern of non-water solubility on a water-soluble film, making wet the water-soluble film of the transfer film with water, immersing an article (an object to be pattern-transferred) into the water in the transfer tub while contacting the transfer film, and transferring the print pattern of the transfer film on a surface of the article using the water pressure generated when the article is immersed into water to form a print layer.
In this water pressure transfer method, although the transfer film is obtained by printing the print pattern on the water-soluble film by gravure printing method etc., this transfer film is generally supplied to the water pressure transfer operation site by being shipped in a roll state after the ink of the print pattern is dried.
The water pressure transfer is performed for the purpose of decorating the surface of the article which is the object to be pattern-transferred. However, lately, a cubic effect is required to be imparted to the surface of the article together as well as the decoration of the article. To comply with this requirement, various unevenness imparting arts have been conventionally adopted.
One of the conventional unevenness imparting arts is a method of printing a pattern on a fine uneven surface of a decorative sheet having the fine uneven surface formed beforehand (see Patent Document 1). Since this conventional method must form the uneven surface beforehand on the decorative sheet by an embossment process or when the decorative sheet is formed, a separate processing operation before the decoration process is required or a peculiar forming mold is required. In addition thereto, voids tend to be produced under the pattern because the pattern which should be adhered to the uneven surface of the article cannot be adhered to the surface of the article while it fully imitates the uneven surface of the article and therefore the pattern is possibly damaged. Furthermore, since the decorative sheet has to be adhered to the article to be decorated, the effectiveness of the operation is disadvantageously lower in comparison with a direct decorative process for the article to be decorated.
Another conventional method is a method in which wood flour is mixed into an ink layer etc. of a print pattern of a transfer film to give a fine unevenness to the surface of the water pressure transfer article (see Patent Document 2). This method can impart an unevenness at the same time of the water pressure transfer, but since the unevenness obtained by this method is limited to the one in the form of dots, a feeling of unevenness of arbitrary forms such as like a feeling of unevenness like a line of bark, for example other than the dot-like unevenness cannot be obtained and therefore use limits are narrowed. Furthermore, printing the print pattern while the granular mixture ingredient such as wood flour placed into ink will have an undesirable influence to the formation of the print pattern and will also possibly cause much trouble in quality, characteristic, etc. of the pattern.
Further conventional method is a method in which a fine unevenness is formed on the surface of the article with a base coat layer having an surface unevenness applied to the article before the transfer of the print pattern or a topcoat having variant unevenness formed by a press-molding machine etc. after the transfer, but before hardening the print pattern (see Patent Documents 3). Since this method does not form a three-dimensional unevenness portion into the print pattern itself, but imparts the feeling of unevenness to the pattern by forming the unevenness in the base coat or the top coat, it cannot be applied to the decorative surface having neither the base coat nor the top coat. Especially, since the step of imparting the unevenness to the top coat is carried out by the press process before being hardened, the process of operation will increase and a real feeling cannot be obtained because the unevenness is not formed in the pattern itself.
There has been proposed a water pressure transfer in which a glossy variation property according to a degree of a fine unevenness is imparted to an ink printed portion of a decorative layer applied to a surface of an article by changing a degree of absorption of particles of an ultraviolet ray hardening resin composite for activating an ink into the ink printed portion according to oil absorption of pigments of an ink, or a concentration of the ink (see Patent Documents 4). Since this method only changes a glossy feeling to the ink printed portion of the decoration layer, a visual cubic effect can be recognized, but a tactile cubic effect felt by actual touch by hand cannot be obtained.
[Patent documents 1] JP05-270199A
[Patent documents 2] JP06-040198A
[Patent documents 3] JP07-276899A
[Patent documents 4] JP3881002 B